Fermentation is a process that was traditionally used to preserve foods. In times gone by, when freezers and fridges didn't exist, the fermentation process allowed food to be stored for long periods of time. Fermentation would begin in the spring and summer months when fruit and veg was being harvested. The food would then be stored to be eaten in the winter months when fresh produce was less readily available. Recently, fermentation has gone through a bit of a revival with many studies and health professionals commending the health benefits these foods offer.
There are so many different ingredients that can be used in the fermentation process, including cabbage, milk, soy beans, tomatoes and more. To initiate fermentation, conditions have to be just right - acidity is needed (usually vinegar), along with salt and heat. Fermentation is a slow process, though it can be quicker if the temperature is warmer, but each combination must generally be left for a few days.
Once the ingredients have fermented, there are many benefits to be gained from eating them. Fermentation can, for example:
Offer more nutrients
Boost the immune system
Aid weight management
Read on to find out why fermented foods offer these benefits.
1. Fermented foods can improve digestion
During fermentation, sugars and starches are converted into lactic acid. This acts as a natural preservative, but also lowers the overall pH of the ingredients. This creates conditions which are perfect for good bacteria known as lactobacilli (probiotics), but which are not so ideal for bad bacteria.
Good bacteria are beneficial for the digestive system, helping to digest food more effectively and keep pathogens at bay, so, as they are able to thrive in fermented foods, we could see some improvements by eating these foods. An imbalance of gut bacteria is also thought to have a major influence over IBS symptoms like bloating, flatulence and diarrhoea so, for some sufferers, fermented foods could be particularly helpful in easing or reducing symptoms.
Processed foods and sugary products, which feature in many everyday diets, can allow bad bacteria to flourish instead and digestive problems to arise. Good bacteria are therefore needed to restore the balance which explains further why fermented foods could be of benefit.
2. Fermented foods offer more nutrients
As we can now see, the preservation of vegetables and fruits by the process of lacto-fermentation has a number of advantages beyond those of simple preservation. An increase in the number of good bacteria in fermented vegetables enhances their digestibility, as I have just explained, but it also increases overall vitamin levels.
Captain Cook, the famous British explorer, required all his sailors to eat sauerkraut (a fermented cabbage) in order to prevent scurvy on his ships. Scurvy is caused by vitamin C deficiency and here it came about due to a lack of fresh produce on long voyages. The vitamin C levels of cabbage are increased by fermentation so we can see how it kept scurvy at bay.
The nutrients in fermented foods become more accessible because sugars and starches are already broken down. Also, carbohydrates, which are harder to absorb, are already partly broken down so they too become easier to offer more nutrients when fermented.
In addition, fermentation can break down phytic acid, a natural substance which is found in plant seeds and legumes. This usually risks binding minerals such as zinc and iron together, meaning they become difficult for the body to absorb. By breaking phytic acid down, though, fermentation makes these minerals available once more.
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The fact that fermented foods provide extra nutrients also explains why they can have a positive influence on the immune system. Vitamin C, for example, is more abundant in fermented foods like sauerkraut and as this nutrient helps to strengthen the immune system, it may help to reduce the frequency of colds and flu.1
Also, many of our immune cells are located in the gut so, if you are keeping your digestive system happy by eating plenty of fermented foods, this should, in turn, have a positive effect on the immune system.
Although lifestyle and dietary changes are still the most effective way to manage weight, fermented foods may bring additional benefits here. A number of studies have indicated that the good bacteria found in fermented foods could help people lose weight.2 The reasons for this are still being explored, though one Japanese study found that good bacteria could reduce the amount of fat we absorb from our food,3 whilst another suggested that good bacteria could influence satiety hormones so that we begin to feel fuller after eating less.4 As I say, this is an area where the research is very much on-going, but it is an interesting theory nonetheless!
5. Fermented foods could influence mood
Research has shown a clear link between the gut and brain5 and so it seems that, if we keep the gut happy, our mood could benefit. Again, this is something that still warrants further attention by researchers but so far the results are promising.6
Popular fermented foods
Now that I've explained all of the potential health benefits that come with eating fermented foods, you may be tempted to try a little yourself! Now, there are several ways in which you can incorporate fermented foods into your diet. Some popular options include:
Sauerkraut – cabbage makes up the base of this dish. It is a good source of vitamin C and K, as well as magnesium and iron.
Kombucha – this is a fermented tea that contains B vitamins and vitamin C.
Miso – a combination of soybeans with salt and other ingredients like rice. It is high in iron, magnesium potassium and calcium.
Lassi – this one is a mix of yoghurt, water, spices and occasionally fruit. It is usually sweet tasting but herbal ones can be made as well.
Yoghurt – I'm sure you know what this one is! Yoghurt is made by fermenting milk and contains plenty of calcium and vitamin B6.
Sourdough bread – to make this kind of bread, the dough is fermented. It has a slightly sour taste which I think goes well some avocado and egg!
Kefir – this too is fermented milk so has similar benefits as yoghurt, only it is a little thinner.
Kimchi – a Korean dish made from a mix of fermented vegetables, salt and spices. There are many different varieties of kimchi, each with their own nutritional benefits.
Tempeh –fermented soybeans make up this dish. It contains calcium alongside magnesium, iron and more.
Apple cider vinegar – this is produced from fermented apple juice. It has a wide range of purposes – often being incorporated into salad dressings and chutneys for added flavour.